The invention relates to an ignition device for an internal combustion engine, a controller for said ignition device, and an ignition unit.
With internal combustion engines without automatic ignition, ignition of the fuel mixture in the combustion areas of the internal combustion engine generally takes place by means of a spark plug, across which an ignition coil discharges.
It is important here that before the sparking process a sufficiently large quantity of energy is stored in the ignition coil, in order to be able to trigger an ignition spark, which requires a correspondingly large electric current through the ignition coil.
On the other hand the level of electrical energy stored in the ignition coil should also not be too high, as this results in an increased thermal load on the ignition coil and ignition output stage and also increases wear and tear on the spark plug.
Before every ignition process therefore the electrical energy stored in the ignition coil should be within a predefined band, in order to enable an ignition spark to be triggered reliably with a minimal thermal load on the ignition coil and ignition output stage and the lowest possible level of wear and tear on the spark plug.
Ignition output stages to activate the spark plug are known, which are integrated in the electronic engine control unit (ECU). This has the advantage that the electronic engine control unit can detect the current through the ignition coil in order to prevent a further increase in current once the required level of energy is reached in the ignition coil.
It can however be desirable to configure the ignition output stage as a separate component from the electronic engine control unit, whereby the electronic engine control unit transmits the ignition signals to the ignition output stage across a control line.
A disadvantage of such a separate configuration of the electronic engine control unit and the ignition output stage is the fact that the electronic engine control unit is not able to check the electrical energy stored in the ignition coil. Therefore when current is being fed to the ignition coil before the ignition processes, significant safety reserves have to be provided, so that the level of electrical energy stored in the ignition coil is usually higher than necessary, resulting in an increased thermal load on the ignition coil and ignition output stage and also increasing wear and tear on the spark plug.
It is known from RODENHEBER, R: Neue Treibergeneration fxc3xcr Kfz-Zxc3xcndsysteme (New driver generation for vehicle ignition systems), Elektronik 19/1991, that the ignition coil current can be transmitted from the ignition output stage across a bi-directional control line to the controller, whereby digital gauges are used on the control line.
It is also known from DE 38 00 932 A1 that a controllable current source can be used to feed the ignition coil current back from the ignition output stage to the controller, said controllable current source inputting a predefined current on the control line based on the ignition coil current.
A similar bi-directional data transmission for a vehicle data bus is also known from U.S. Pat. No. 4,736,367.
A disadvantage of the known arrangement is however the fact that only the ignition coil current is transmitted.
The object of the invention is therefore to make it possible with a separate arrangement of ignition output stage and electronic engine control unit for a plurality of different items of information to be fed back from the ignition output stage to the engine control unit across a single bi-directional control line.
The object can be achieved by an ignition unit with an ignition device and a controller for an internal combustion engine, the ignition device comprising an output for electrical activation of an ignition element for a combustion area of the internal combustion engine, an electrical energy storage device for storing the electrical energy required to activate the ignition element, a control input to record a control signal controlling the charging process for the energy storage device and/or the ignition process from the controller, wherein the control input enables bi-directional data transmission with the controller, in order to give the controller feedback about the charging process for the energy storage device and/or the ignition process for the ignition element, while the control input is connected to a controllable current source in order to input a current signal at the control input to feed back to the controller, wherein the energy storage device is connected to a current metering unit, which records the charging current of the energy storage device, and a controllable sink connected to the control input, in order to input a current signal at the control input to feed back to the controller, whereby the current metering unit is connected to the controllable current sink or to the controllable current source, and the energy storage device is connected to a voltage metering unit, which monitors the ignition voltage, whereby the output side of the voltage metering unit is connected to the controllable current source or the controllable current sink, in order to input the current signal at the control input based on the ignition voltage, the controller comprising a control output for emitting a control signal controlling the charging process for the energy storage device located in the ignition device and/or the ignition process for an ignition element, a driver circuit connected to the control output to generate the control signal, whereby the control output enables bi-directional data transmission, in order to be able to receive feedback from the ignition device about the charging process for the energy storage device and/or the ignition process, a first current metering unit connected to the control output, in order to detect a current signal input by the ignition device, and a second current metering unit connected to the control output, wherein the first current metering unit detects a current signal input by a controllable current sink in the ignition device, while the second current metering unit detects a current signal input by a controllable current source in the ignition device, and the two current metering units are each connected across a controllable switching element to the control output, wherein the controller is connected to the ignition device across a bi-directional control and diagnosis line.
The object can be achieved by an ignition device for an internal combustion engine, comprising an output for electrical activation of an ignition element for a combustion area of the internal combustion engine, an electrical energy storage device for storing the electrical energy required to activate the ignition element, a control input to record a control signal controlling the charging process for the energy storage device and/or the ignition process from a controller, wherein the control input enables bi-directional data transmission with the controller, in order to give the controller feedback about the charging process for the energy storage device and/or the ignition process for the ignition element, while the control input is connected to a controllable current source in order to input a current signal at the control input to feed back to the controller, wherein the energy storage device is connected to a current metering unit, which records the charging current of the energy storage device, and a controllable sink connected to the control input, in order to input a current signal at the control input to feed back to the controller, whereby the current metering unit is connected to the controllable current sink or to the controllable current source, and the energy storage device is connected to a voltage metering unit, which monitors the ignition voltage, whereby the output side of the voltage metering unit is connected to the controllable current source or the controllable current sink, in order to input the current signal at the control input based on the ignition voltage.
The current metering unit may have a precision resistor, which is connected in series to the energy storage device, whereby the precision resistor is connected to an input of a comparator, which compares the voltage decreasing across with precision resistor with a reference current value and activates the controllable current source or the controllable current sink if the reference current value is exceeded. The voltage metering unit may comprise a comparator with two inputs, between which the energy storage device is connected, whereby the comparator activates the controllable current source or the controllable current sink, if a predefined reference voltage value is exceeded. The energy storage device can be connected across a protective resistor to the comparator.
The object can also be achieved by a controller for an ignition device in an internal combustion engine, comprising a control output for emitting a control signal controlling the charging process for an energy storage device located in the ignition device and/or the ignition process for an ignition element, a driver circuit connected to the control output to generate the control signal, whereby the control output enables bi-directional data transmission, in order to be able to receive feedback from the ignition device about the charging process for the energy storage device and/or the ignition process, a first current metering unit connected to the control output, in order to detect a current signal input by the ignition device, and a second current metering unit connected to the control output, wherein the first current metering unit detects a current signal input by a controllable current sink in the ignition device, while the second current metering unit detects a current signal input by a controllable current source in the ignition device, and the two current metering units are each connected across a controllable switching element to the control output.
The control output can be connected to a voltage driver in order to transmit a voltage signal to the ignition device.
The invention embraces the general technical doctrine of enabling a bi-directional data transmission between the controller and the ignition device with a separate configuration of ignition output stage or ignition device on the one hand and electronic engine control unit or controller on the other hand, so that the ignition device can feed back for example the charge status of the ignition coil to the controller.
Instead of or in addition to the charge status of the ignition coil, there is also the possibility of transmitting other information from the ignition device to the controller, such as for example spark combustion duration or the current threshold value of the ignition coil turn-off current.
According to the invention the transmission of information from the ignition device to the controller takes place with the ignition device inputting a current signal on the connecting line between the controller and the ignition device. This is done for example by the ignition device increasing or reducing the electric current drawn from the controller in normal operation across the connecting line by a predefined current adjustment.
According to the invention the ignition device here has a controllable current sink and a controllable current source, which is connected to the control input. When the controllable current sink is activated, the electric current drawn from the controller is increased, while the electric current drawn from the controller is reduced when the controllable current source in the ignition device is activated, each of which processes can be identified by the controller.
For this purpose the controller preferably has at least one current metering unit, which detects the electric current drawn from the ignition device and as a result can identify activation of the controllable current source or the controllable current sink in the ignition device.
It has already been stated above that it is desirable for the ignition device to notify the separate controller of the charge status of the ignition coil, so that the charging process for the ignition coil or the starting up of the electric current through the ignition coil can be started promptly. According to the invention therefore a current metering unit is provided which measures the electric current flowing through the ignition coil and is connected on the output side to the controllable current source or the controllable current sink, in order to transmit a corresponding signal to the controller when a predefined threshold value for the electric current flowing through the ignition coil is reached or exceeded. Preferably the current flowing through the ignition coil is measured here by a precision resistor connected in series to the ignition coil and connected to the input of a comparator, whereby the comparator measures the decreasing voltage across the precision resistor, which is proportional to the electric current flowing through the ignition coil. The comparator here compares the identified current value with a predefined reference current value and activates the controllable current source or the controllable current sink, if the reference current value is exceeded.
Within the context of the invention it is also possible for the ignition device to notify the controller of the spark combustion duration. According to the invention therefore a voltage metering unit connected to the ignition coil is provided, which monitors the ignition voltage, whereby the voltage metering unit is connected on the output side to the controllable current source or the controllable current sink, in order to supply a signal based on the ignition voltage to the controller. In the preferred embodiment the voltage metering unit is connected on the output side to a comparator, which compares the measured ignition voltage with predefined reference voltage value and activates the controllable current source or the controllable current sink if said voltage is above or below the predefined reference voltage value.
The signals transmitted by the ignition device are preferably analyzed in the controller by a current metering unit, which detects the electric current drawn from the ignition device across the connecting line. The current metering unit here preferably comprises a comparator, which compares the measured current value with a predefined reference current value and generates a digital output signal accordingly.